The use of sophisticated placement machines in manufacturing printed circuit or similar cards, boards, panels, etc. is well known. The term printed circuit board (PCB) is used herein is to refer to any such electronic packaging structure. Typically, reels of tape-mounted circuit components are supplied to the placement machine by multiple feeders, each feeder holding a reel of components. Components are provided at a pick station by each feeder assembly. A pick/place head, having a vacuum spindle equipped with a vacuum nozzle, may be moved in the Z-axis as well as along the X and Y axes. The vacuum nozzle is sized and otherwise configured for use with each different size and style of component to be placed by the machine. In operation, the pick/place head is moved to the pick station and the nozzle positioned over the tape-mounted component. The vacuum nozzle is lowered to a point where, upon application of vacuum, the component is removed from its backing tape, centered, and held tightly against the nozzle orifice. The pick/place head is then moved to a point over the printed circuit board being assembled and the component deposited on the printed circuit board at a predetermined location.
Several problems must be addressed in this seemingly simple operation. First, as component sizes have shrunk, the accuracy of placement of the vacuum nozzle over the component for picking has become more critical. Typically, calibration routines are performed upon machine setup or periodically as required for operation of the machine. With micro-miniature components, small variations occurring over time can quickly lead to inaccurate picking and/or placement of these components.
Vacuum nozzles have also shrunk commensurately to maintain compatibility with these shrinking component sizes. Consequently, the vacuum nozzles have become more fragile and more readily damaged. Damage may occur while a nozzle is being installed on a pick/place head or during the actual pick/place operation of the component placement machine.
A third problem is that the adhesive typically used to hold surface mount and similar components in place until a solder reflow operation may contaminate the nozzle. Likewise, small particles of dirt or debris may lodge in the nozzle. As nozzle orifice sizes have shrunk, the effects of these contaminants have become more critical to reliable operation of the placement machine.
Currently, component placement machines utilize multi-spindle pick/place heads to improve assembly speed. Each head contains multiple vacuum spindles, each having its own vacuum nozzle. With multi-spindle machines, the need for real-time monitoring of the vacuum nozzle condition becomes even more critical. One damaged or contaminated nozzle can be difficult to locate based on intermittent placement problems on the printed circuit boards being assembled.